Benzene derivatives, and liquid-crystalline medium

ABSTRACT

The invention relates to a liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR1## in which R, A 1 , A 2 , Z 1 , Z 2 , X, L and m are as defined in claim 1.

This application is a continuation of application Ser. No. 08/362,574,filed Jan. 9, 1995 now abandoned, which is a 371 of PCT/EP94/01364,filed Apr. 29, 1994, abandoned.

The present invention relates to benzene derivatives and to aliquid-crystalline medium, to the use of the latter for electroopticalpurposes, and to displays containing this medium.

BACKGROUND OF INVENTION

Liquid crystals are used, in particular, as dielectrics in displaydevices since the optical properties of such substances can be effectedby an applied voltage. Electrooptical devices based on liquid crystalsare extremely well known to those skilled in the art and may be based onvarious effects. Devices of this type are, for example, cells havingdynamic scattering, DAP (deformation of aligned phases) cells,guest/host cells, TN cells having a twisted nematic structure, STN(super-twisted nematic) cells, SBE (super-birefringence effect) cellsand OMI (optical mode interference) cells. The most common displaydevices are based on the Schadt-Helfrich effect and have a twistednematic structure.

The liquid-crystal materials must have good chemical and thermalstability and good stability toward electrical fields andelectromagnetic radiation. Furthermore, the liquid-crystal materialsshould have low viscosity and give short addressing times, low thresholdvoltages and high contrast in the cells. Furthermore, they should have asuitable mesophase, for example, for the abovementioned cells, a nematicor cholesteric mesophase, at customary operating temperatures, i.e. inthe broadest possible range above and below room temperature. Sinceliquid crystals are generally used as mixtures of a plurality ofcomponents, it is important that the components are readily misciblewith one another. Further properties, such as electrical conductivity,dielectric anisotropy and optical anisotropy, must meet variousrequirements depending on the cell type and the area of application. Forexample, materials for cells having a twisted nematic structure shouldhave positive dielectric anisotropy and low electrical conductivity.

For example, the media desired for matrix liquid-crystal displayscontaining integrated nonlinear elements for switching individual imagepoints (MLC displays) are those having high positive dielectricanisotropy, broad nematic phases, relatively low birefringence, veryhigh specific resistance good UV and temperature stability of theresistance and a low vapor pressure.

Matrix liquid-crystal displays of this type are known. Examples ofnonlinear elements which can be used to individually switch theindividual image points are active elements (i.e. transistors). This isthen referred to as an "active matrix", and a differentiation can bemade between two types:

1. MOS (Metal Oxide Semiconductor) or other diodes on a silicon wafer assubstrate.

2. Thin-film transistors (TFTs) on a glass plate as substrate.

The use of monocrystalline silicon as the substrate material limits thedisplay size since even the modular assembly of the various partdisplays results in problems at the joints.

In the case of the more promising type 2, which is preferred, theelectrooptical effect used is usually the TN effect. A differentiationis made between two technologies: TFTs comprising compoundsemiconductors, such as, for example, CdSe, or TFTs based onpolycrystalline or amorphous silicon. Intensive research efforts arebeing made worldwide in the latter technology.

The TFT matrix is applied to the inside of one glass plate of thedisplay, while the inside of the other glass plate carries thetransparent counterelectrode. Compared with the size of the image pointelectrode, the TFT is very small and hardly affects the image at all.This technology can also be extended to fully color-compatible imagedisplays, where a mosaic of red, green and blue filters is arranged insuch a manner that each filter element is located opposite a switchableimage element.

The TFT displays usually operate as TN cells with crossed polarizers intransmission and are illuminated from the back.

The term MLC display here covers any matrix display containingintegrated nonlinear elements, i.e. in addition to the active matrix,also displays containing passive elements such as varistors or diodes(MIM=metal-insulator-metal).

MLC displays of this type are particularly suitable for TV applications(for example pocket TV sets) or for high-information displays forcomputer applications (laptops) and in automobile or aircraftconstruction. In addition to problems with respect to the angledependency of the contrast and the switching times, problems result inMLC displays due to inadequate specific resistance of the liquid-crystalmixtures TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E.,SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay84, September 1984: A 210-288, Matrix LCD Controlled by Double StageDiode Rings, p. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84,September 1984: Design of Thin Film Transistors for Matrix Adressing ofTelevision Liquid Crystal Displays, p. 145 ff., Paris. As the resistancedecreases, the contrast of an MLC display worsens and the problem of"afterimage elimination" may occur. Since the specific resistance of theliquid-crystal mixture generally decreases over the life of an MLCdisplay due to interactions with the internal surfaces of the display, ahigh (initial) resistance is very important to give acceptable servicelives. In particular in the case of low-voltage mixtures, it washitherto not possible to achieve very high specific resistances. It isfurthermore important that the specific resistance increases as littleas possible with increasing temperature and after heating and/orexposure to UV radiation. The low-temperature properties of the mixturesfrom the prior art are also particularly disadvantageous. It is requiredthat crystallization and/or smectic phases do not occur, even at lowtemperatures, and that the temperature dependence of the viscosity is aslow as possible. The MLC displays of the prior art thus do not satisfycurrent demands.

Thus, there continues to be a great demand for MLC displays of very highspecific resistance and at the same time a broad operating temperaturerange, short switching times, even at low temperatures and low thresholdvoltage which do not have these disadvantages or only do so to a lesserextent.

For TN (Schadt-Helfrich) cells, media are desired which facilitate thefollowing advantages in the cells:

broadened nematic phase range (in particular down to low temperatures),

switchability at extremely low temperatures (outdoor use, automobiles,avionics),

increased stability to UV radiation (longer life).

The media available from the prior art do not make it possible toachieve these advantages whilst simultaneously retaining the otherparameters.

For supertwisted (STN) cells, media are desired which have a greatermultiplexing ability and/or lower threshold voltages and/or broadernematic phase ranges (in particular at low temperatures). To this end, afurther extension of the parameter latitude available (clearing point,smectic-nematic transition or melting point, viscosity, dielectricvalues, elastic values) is urgently desired.

SUMMARY OF THE INVENTION

The invention has the object of providing media, in particular for MLC,TN or STN displays of this type, which do not have the abovementioneddisadvantages or only do so to a lesser extent, and preferably at thesame time have very high specific resistances and low thresholdvoltages.

It has now been found that this object can be achieved if mediaaccording to the invention are used in displays.

The invention thus relates to a liquid-crystalline medium based on amixture of polar compounds having positive dielectric anisotropy,characterized in that it contains one or more compounds of the generalformula I ##STR2## in which R is H, an alkyl or alkenyl radical having 1to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF₃or at least monosubstituted by halogen, it also being possible for oneor more CH₂ groups in these radicals to be replaced, in each caseindependently of one another, by --O--, --S--, --⋄--, --CO--, --CO--O--,--O--CO-- or --O--CO--O--, in such a way that O atoms are not linkeddirectly to one another

A¹ and A² are each, independently of one another, a

(a) trans-1,4-cyclohexylene radical in which, in addition, one or morenon-adjacent CH₂ groups may be replaced by --O-- and/or --S--,

(b) 1,4-phenylene radical in which, in addition, one or two CH groupsmay be replaced by N, or

(c) radical from the group consisting of 1,4-cyclohexenylene,1,4-bicyclo(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl,decahydronaphthalene-2,6-diyl and1,2,3,4-tetrahydronaphthalene-2,6-diyl,

it being possible for the radicals (a) and (b) to be substituted by oneor two fluorine atoms,

Z¹ and Z² are each, independently of one another, --CO--O--, --O--CO--,--CH₂ O--, --OCH₂ --, --CH₂ CH₂ --, --CH═CH--, --C.tbd.C-- or a singlebond, and one of the radicals Z¹ and Z² is alternatively --(CH₂)₄ -- or--CH═CH--CH₂ CH₂ --,

X is halogenated alkyl, alkoxy, alkenyl or alkenyloxy, in each casehaving 1 to 6 carbon atoms,

L is F and also H when X is OCF₃, OCF₂ H or OC₂ F₅, and

m is 0, 1 or 2.

Particular preference is given to mixtures containing compounds of theformula I and all sub-formulae in which A¹ is 1,4-phenylene which ismono-substituted or disubstituted by F or monosubstituted by CN. Theseare in particular 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene,3,5-difluoro-1,4-phenylene, 2-cyano-1,4-phenylene and3-cyano-1,4-phenylene.

In the formula I, Z¹ and Z² are preferably a single bond and --CH₂ CH₂--, secondarily preferably --CH₂ O--, --OCH₂ --, --O--CO-- and--CO--O--. If one of the radicals Z¹ and Z² is --(CH₂)₄ -- or--CH═CH--CH₂ CH₂ --, the other radical Z¹ or Z² (if present) ispreferably the single bond.

If R is an alkyl radical and/or an alkoxy radical, this may bestraight-chain or branched. It is preferably straight-chain, has 2, 3,4, 5, 6 or 7 carbon atoms and accordingly is preferably ethyl, propyl,butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxyor heptoxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy,undecoxy, dodecoxy, tridecoxy or tetradecoxy.

Oxaalkyl is preferably straight-chain 2-oxapropyl (═methoxymethyl), 2-(═ethoxymethyl) or 3-oxabutyl (═2-methoxyethyl), 2-, 3- or 4-oxapentyl,2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-,6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, or 2-, 3-, 4-,5-, 6-, 7-, 8- or 9-oxadecyl.

If R is an alkyl radical in which one CH₂ group has been replaced by--CH═CH--, this may be straight-chain or branched. It is preferablystraight-chain and has 2 to 10 carbon atoms. It is accordingly inparticular vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-,-2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-,-3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl,non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, or dec-1-, -2-, -3-,-4-, -5-, -6-, -7-, -8- or -9-enyl.

If R is an alkyl radical in which one CH₂ group has been replaced by--O-- and one has been replaced by --CO--, these are preferablyadjacent. These thus contain an acyloxy group --CO--O-- or anoxycarbonyl group --O--CO--. These are preferably straight-chain andhave 2 to 6 carbon atoms.

They are accordingly in particular acetoxy, propionyloxy, butyryloxy,pentanoyloxy, hexanoyloxy, acetoxymethyl, propionyloxymethyl,butyryloxymethyl, pentanoyloxymethyl, 2-acetoxyethyl,2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetoxypropyl,3-propionyloxypropyl, 4-acetoxybutyl, methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl,ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl,2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl,2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl,3-(ethoxycarbonyl)propyl or 4-(methoxycarbonyl)butyl.

If R is an alkyl radical in which one CH₂ group has been replaced byunsubstituted or substituted-CH═CH-- and an adjacent CH₂ group has beenreplaced by CO or CO--O or O--CO, this may be straight-chain orbranched. It is preferably straight-chain and has 4 to 13 carbon atoms.It is accordingly in particular acryloyloxymethyl, 2-acryloyloxyethyl,3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl,6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl,9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl,2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl,5-methacryloyloxypentyl, 6-methacryloyloxyhexyl,7-methacryloyloxyheptyl, 8-methacryloyloxyoctyl or9-methacryloyloxynonyl.

If R is an alkyl or alkenyl radical which is monosubstituted by CN orCF₃, this radical is preferably straight-chain. The substitution by CNor CF₃ is in any desired position.

If R is an alkyl or alkenyl radical which is at least monosubstituted byhalogen, this radical is preferably straight-chain and halogen ispreferably F or Cl. In the case of multiple substitution, halogen ispreferably F. The resulting radicals also include perfluorinatedradicals. In the case of monosubstitution, the fluorine or chlorinesubstituent may be in any desired position, but is preferably in theω-position.

Compounds of the formula I which contain wing groups R which aresuitable for polymerization reactions are suitable for the preparationof liquid-crystalline polymers.

Compounds of the formula I containing branched wing groups R mayoccasionally be of importance due to better solubility in the customaryliquid-crystalline base materials, but in particular as chiral dopes ifthey are optically active. Smectic compounds of this type are suitableas components of ferroelectric materials.

Compounds of the formula I having S_(A) phases are suitable, forexample, for thermally addressed displays.

Branched groups of this type generally contain not more than one chainbranch. Preferred branched radicals R are isopropyl, 2-butyl(═1-methylpropyl), isobutyl (═2-methylpropyl), 2-methylbutyl, isopentyl(═3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl,2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy,3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy,1-methylhexoxy and 1-methylheptoxy.

If R is an alkyl radical in which two or more CH₂ groups have beenreplaced by --O-- and/or --CO--O--, this may be straight-chain orbranched. It is preferably branched and has 3 to 12 carbon atoms. It isaccordingly in particular biscarboxymethyl, 2,2-biscarboxyethyl,3,3-biscarboxypropyl, 4,4-biscarboxybutyl, 5,5-biscarboxypentyl,6,6-biscarboxyhexyl, 7,7-biscarboxyheptyl, 8,8-biscarboxyoctyl,9,9-biscarboxynonyl, 10,10-biscarboxydecyl, bis(methoxycarbonyl)methyl,2,2-bis(methoxycarbonyl)ethyl, 3,3-bis(methoxycarbonyl)propyl,4,4-bis(methoxycarbonyl)butyl, 5,5-bis(methoxycarbonyl)pentyl,6,6-bis(methoxycarbonyl)hexyl, 7,7-bis(methoxycarbonyl)heptyl,8,8-bis(methoxycarbonyl)octyl, bis(ethoxycarbonyl)methyl,2,2-bis(ethoxycarbonyl)ethyl, 3,3-bis(ethoxycarbonyl)propyl,4,4-bis(ethoxycarbonyl)butyl or 5,5-bis(ethoxycarbonyl)hexyl.

The 1,4-cyclohexenylene group preferably has the following structures:##STR3##

The invention also relates to novel compounds of the formulae I1 and I2:##STR4## in which R is as defined above, and r is 0 or 1, and x is 0, 1or 2.

Some compounds of the formulae I1 and I2 are covered by the generalformulae in WO 89/02884, WO 91/03450 and WO 91/08184. However, theadvantageous effects of tetrafluorobiphenyls as components ofliquid-crystalline media are not mentioned.

The compounds of the formulae I1 and I2 can, like similar compounds, forexample known from WO 89/02884, be used as components ofliquid-crystalline media, in particular for displays based on theprinciple of the twisted cell. They have a broad range of applications.Depending on the choice of substituents, these compounds can be used asbase materials of which the liquid-crystalline media are predominantlycomposed; however, compounds of the formula I can also be added toliquid-crystalline base materials from other classes of compound inorder, for example, to modify the dielectric and/or optical anisotropyof dielectrics of this type and/or to optimize its threshold voltageand/or its viscosity.

In the pure state, the compounds of the formula I are colorless and formliquid-crystalline mesophases in a temperature range which is favorablylocated for electro-optical use. They are stable chemically, thermallyand to light.

The preferred radicals for compounds of the formula I also apply to thecompounds I1 and I2.

The compounds of the formula I are prepared by methods known per se, asdescribed in the literature (for example in the standard works, such asHouben-Weyl, Methoden der Organischen Chemie, Georg-Thieme-Verlag,Stuttgart), to be precise under reaction conditions which are known andsuitable for said reactions.

Use may also be made here of variants which are known per se, but arenot described here in greater detail.

The compounds according to the invention can be prepared, for example,by metallating a compound of formula II* ##STR5## in which R, A¹, A²,Z¹, Z², L and m are as defined above, in accordance with the reactionscheme below, and subsequently reacting the product with a suitableelectrophile.

The compounds of the formulae I1 and I2 can be prepared as follows:##STR6##

Compounds of the formula I in which R is OC₂ F₅ can be prepared, forexample, as follows: ##STR7##

Further synthetic methods are evident to the person skilled in the art.For example, appropriately 5-substituted 1,3-difluorobenzene compoundsor monofluorinated analogues (L=H) can be converted into the1,3-difluoro compounds or monofluorinated analogues (L=H) in accordancewith the above scheme, and the radical R--(A¹ --Z¹)_(m) can subsequentlybe introduced by reactions which are customary in liquid-crystalchemistry (for example esterification, etherification or coupling, forexample as described in the article by E. Poetsch, Kontakte (Darmstadt),1988 (2), p. 15).

The compounds of the formula II* can be prepared, for example, inaccordance with the synthetic schemes below: ##STR8##

Starting materials are either known or can be prepared analogously toknown compounds.

Esters of the formula I can also be obtained by esterifyingcorresponding carboxylic acids (or reactive derivatives thereof) usingalcohols or phenols (or reactive derivatives thereof) or by the DCCmethod (DCC=dicyclohexylcarbodiimide).

The corresponding carboxylic acids and alcohols or phenols are known orcan be prepared analogously to known processes.

In a further process for the preparation of the compounds of the formulaI, an aryl halide is reacted with an olefin in the presence of atertiary amine and in the presence of a palladium catalyst (cf. R. F.Heck, Acc. Chem. Res. 12 (1979) 146). Examples of suitable aryl halidesare chlorides, bromides and iodides, in particular bromides and iodides.The tertiary amines necessary for the success of the coupling reaction,such as, for example, triethylamine, are also suitable as solvent.Examples of suitable palladium catalysts are palladium salts, inparticular Pd(II) acetate, with organophosphorus(III) compounds, suchas, for example, triarylphosphines. The reaction can be carried out inthe presence or absence of an inert solvent at temperatures betweenabout 0° and 150°, preferably between 20° and 100°; examples of suitablesolvents are nitriles, such as acetonitrile, or hydrocarbons, such asbenzene or toluene. The aryl halides and olefins employed as startingmaterials are in many cases commercially available or can be prepared byprocesses known from the literature, for example by halogenation ofcorresponding parent compounds or by elimination reactions oncorresponding alcohols or halides.

In this way, for example, stilbene derivatives can be prepared. Thestilbenes can furthermore be prepared by reacting a 4-substitutedbenzaldehyde with a corresponding phosphorus ylide by the Wittig method.However, tolans of the formula I can also be prepared by employingmonosubstituted acetylene instead of the olefin (Synthesis 627 (1980) orTetrahedron Lett. 27, 1171 (1986)).

Aromatic compounds can furthermore be coupled by reacting aryl halideswith aryltin compounds. These reactions are preferably carried out withaddition of a catalyst, such as, for example, a palladium(O) complex, ininert solvents, such as hydrocarbons, at high temperatures, for examplein boiling xylene, under a protective gas.

Coupling reactions of alkynyl compounds with aryl halides can be carriedout analogously to the process described by A. O. King, E. Negishi, F.J. Villani and A. Silveira in J. Org. Chem. 43, 358 (1978).

Tolans of the formula I can also be prepared by theFritsch-Buttenberg-Wiechell rearrangement (Ann. 279, 319, 1984), inwhich the 1,1-diaryl-2-haloethylenes are rearranged to diarylacetylenesin the presence of strong bases.

Tolans of the formula I can also be prepared by brominating thecorresponding stilbenes and then subjecting the products todehydrohalogenation. Use may be made here of variants which are knownper se, but are not described here in greater detail.

Ethers of the formula I are obtainable by etherifying the correspondinghydroxyl compounds, preferably corresponding phenols, the hydroxylcompound expediently first being converted into a corresponding metalderivative, for example into the corresponding alkali metal alkoxide oralkali metal phenoxide by treatment with NaH, NaNH₂, NaOH, KOH, Na₂ CO₃or K₂ CO₃. This can then be reacted with the corresponding alkyl halide,alkyl sulphonate or dialkyl sulphate, expediently in an inert solvent,such as, for example, acetone, 1,2-dimethoxyethane, DMF or dimethylsulphoxide, or alternatively with an excess of aqueous oraqueous-alcoholic NaOH or KOH, at temperatures between about 20° and100° C.

The compounds of the formula I in which R=alkenyl can be obtained fromthe corresponding cyano compounds (R=CN), which are converted into thealdehydes (R=CHO) using diisobutylaluminum. For example, in successivesteps, a methylene group can be introduced by a Wittig reaction of thealdehyde with methoxymethyl-triphenylphosphonium chloride, followed byhydrolysis of the resultant enol ether (for example using dilutehydrochloric acid).

The starting materials are either known or can be prepared analogouslyto known compounds.

The compounds having a --(CH₂)₄ -- bridge can be prepared in accordancewith the following scheme: ##STR9##

In the Pd(II)-catalyzed coupling reaction, either the target product I*is formed directly or a precursor is formed into which the radical --Yis introduced entirely analogously to the above methods for compounds ofthe formula I.

The compounds having a --CH═CH--CH₂ CH₂ -- bridge can be prepared by theWittig method in accordance with the following scheme: ##STR10##

The invention also relates to electrooptical displays (in particular STNor MLC displays having two plane-parallel outer plates which, togetherwith a frame, form a cell, integrated nonlinear elements for switchingindividual image points on the outer plates, and a nematicliquid-crystal mixture of positive dielectric anisotropy and highspecific resistance located in the cell) which contain media of thistype, and to the use of these media for electrooptical purposes.

The liquid-crystal mixtures according to the invention facilitate asignificant broadening of the parameter latitude available.

The achievable combinations of clearing point, viscosity at lowtemperature, thermal and UV stability and dielectric anisotropy are farsuperior to the previous materials from the prior art.

The requirement for a high clearing point, a nematic phase at lowtemperature and a high Δε was previously only achievable to anunsatisfactory extent. Although systems such as, for example, ZLI-3119have a comparable clearing point and comparatively favorableviscosities, they have, however, a Δε of only +3.

Other mixture systems have comparable viscosities and values of Δε, butonly have clearing points in the region of 60° C.

The liquid-crystal mixtures according to the invention make it possible,while retaining the nematic phase at down to -20° C. and preferably downto -30° C., particularly preferably down to -40° C., to achieve clearingpoints above 80°, preferably above 90°, particularly preferably above100° C., simultaneously dielectric anisotropy values Δε≧6, preferably≧8, and a high value for the specific resistance, which means thatexcellent STN and MCL displays can be achieved. The mixtures arecharacterized in particular by low operating voltages. The TN thresholds(VIP) are below 2.0 V, preferably below 1.5 V, particularly preferably<1.3 V.

It goes without saying that a suitable choice of the components of themixtures according to the invention also allows higher clearing points(for example above 110°) to be achieved at higher threshold voltages orlower clearing points to be achieved at lower threshold voltages whileretaining the other advantageous properties. It is likewise possible toobtain mixtures of relatively high Δε and thus lower thresholds if theviscosities are increased by a correspondingly small amount. The MLCdisplays according to the invention preferably operate in the firsttransmission minimum of Gooch and Tarry C. H. Gooch and H. A. Tarry,Electron. Lett. 10, 2-4, 1974; C. H. Gooch and H. A. Tarry, Appl. Phys.,Vol. 8, 1575-1584, 1975!; in this case, a lower dielectric anisotropy inthe second minimum is sufficient in addition to particularly favorableelectrooptical properties, such as, for example, high gradient of thecharacteristic line and low angle dependency of the contrast (GermanPatent 30 22 818) at the same threshold voltage as in an analogousdisplay. This allows significantly higher specific resistances to beachieved in the first minimum using the mixtures according to theinvention than using mixtures containing cyano compounds. A personskilled in the art can use simple routine methods to produce thebirefringence necessary for a prespecified layer thickness of the MLCdisplay by a suitable choice of the individual components and theirproportions by weight.

The viscosity at 20° C. is preferably <60 mPa.s, particularly preferably<50 mPa.s. The nematic phase range is preferably at least 90°, inparticular at least 100°. This range preferably extends at least from-20° to +80°.

Measurements of the "capacity holding ratio" (HR) S. Matsumoto et al.,Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference,San Francisco, June 1984, p. 304 (1984); G. Weber et al., LiquidCrystals 5, 1381 (1989)! have shown that mixtures according to theinvention containing compounds of the formula I exhibit a considerablysmaller decrease in the HR with increasing temperature than do analogousmixtures in which the compounds of the formula I are replaced bycyanophenylcyclohexanes of the formula ##STR11##

The UV stability of the mixtures according to the invention is alsoconsiderably better, i.e. they exhibit a significantly smaller decreasein the HR on exposure to UV radiation.

The media according to the invention are preferably based on a plurality(preferably two or more) of compounds of the formula I, i.e. theproportion of these compounds is 5-95%, preferably 10-60% andparticularly preferably in the range 20-50%.

The individual compounds of the formulae I to XVI and their sub-formulaewhich can be used in the media according to the invention are eitherknown or can be prepared analogously to the known compounds.

Preferred embodiments are indicated below:

halogenated in the case of X in formula I means fluorinated and/orchlorinated, but preferably fluorinated

X is preferably OCF₃, OCF₂ H, OC₂ F₅ or OCH═CF₂, or --O--Q--Y, in whichQ is alkylene or alkenylene having 1 to 5 carbon atoms which isunsubstituted or monosubstituted or polysubstituted by fluorine and/orchlorine, and Y is Hal , CHal₃ or CHHal₂, and Hal is F or Cl, preferablyF,

Q is preferably --CH₂ --, --CH₂ CH₂ --, --CHF--, --CF₂ --, --CH₂ CHF--,--CHFCH₂ --, --CH₂ CHF--, --CF₂ CH₂ --, --CH₂ --CH₂ --, --CF₂ CF₂ --,--CH₂ CF₂ --, --CH═CH--, --CH═CF--, --CF═CF--, --CH═CCl--, --CH₂CH═CF--, --CH₂ --CF═CF-- or --CF₂ --CF═CF--,

medium additionally contains one or more compounds selected from thegroup comprising the general formulae II to V: ##STR12## in which theindividual radicals are as defined below: R⁰ : alkyl, oxaalkyl,fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms

X⁰ : F, Cl, CF₃, OCF₃, OCHF₂, OCH═CF₂, OCF═CF₂, OCFH--CF₂ H or OCF₂--CF₂ H

Y¹ and

Y² : each, independently of one another, H or F

r: 0 or 1.

The compound of the formula IV is preferably ##STR13## mediumadditionally contains one or more compounds selected from the groupcomprising the general formulae VI to XII: ##STR14## in which R⁰, Y¹ andY² are each, independently of one another, as defined on claim 2, and X⁰is F, Cl, CF₃, OCF₃, OCHF₂, alkyl, oxaalkyl, fluoroalkyl or alkenyl, ineach case having up to 7 carbon atoms.

The proportion of compounds of the formulae I to V together is at least50% by weight in the total mixture

the proportion of compounds of the formula I is from 3 to 80% by weightin the total mixture

the proportion of compounds of the formulae II to V is from 20 to 80% byweight in the total mixture ##STR15## is preferably ##STR16## the mediumcontains compounds of the formulae II, III, IV or V R⁰ is straight-chainalkyl or alkenyl having 2 to 7 carbon atoms

the medium consists essentially of compounds of the formulae I to V

the medium contains further compounds, preferably selected from thefollowing group comprising the general formulae XIII to XVII: ##STR17##in which R⁰ and X⁰ are as defined in claim 2 and the 1,4-phenylene ringsmay be substituted by CN, chlorine or fluorine. The 1,4-phenylene ringsare preferably mono- or polysubstituted by fluorine atoms.

the I: (II+III+IV+V) weight ratio is preferably from 1:10 to 10:1.

medium essentially comprises compounds selected from the groupcomprising the general formulae I to XII

It has been found that even a relatively small proportion of compoundsof the formula I mixed with conventional liquid-crystal materials, butin particular with one or more compounds of the formula II, III, IVand/or V, results in a significant lowering of the threshold voltage andin low values for the birefringence, and at the same time broad nematicphases with low smectic-nematic transition temperatures are observed, asa result of which the shelf life is improved. The compounds of theformulae I to V are colorless, stable and readily miscible with oneanother and with other liquid-crystal materials.

The term "alkyl" covers straight-chain and branched alkyl groups having1-7 carbon atoms, in particular the straight-chain groups methyl, ethyl,propyl, butyl, pentyl, hexyl and heptyl. Groups having 2-5 carbon atomsare generally preferred.

The term "alkenyl" covers straight-chain and branched alkenyl groupshaving 2-7 carbon atoms, in particular the straight-chain groups.Preferred alkenyl groups are C₂ -C₇ -1E-alkenyl, C₄ -C₇ -3E-alkenyl, C₅-C₇ -4-alkenyl, C₆ -C₇ -5-alkenyl and C₇ -6-alkenyl, in particular C₂-C₇ -1E-alkenyl, C₄ -C₇ -3E-alkenyl and C₅ -C₇ -4-alkenyl. Examples ofparticularly preferred alkenyl groups are vinyl, 1E-propenyl,1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl,3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl,4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groupshaving up to 5 carbon atoms are generally preferred.

The term "fluoroalkyl" preferably covers straight-chain groupscontaining terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl,3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and7-fluoroheptyl. However, other positions of the fluorine are notexcluded.

The term "oxaalkyl" preferably covers straight-chain radicals of theformula C_(n) H_(2n+1) --O--(CH₂)_(m), in which n and m are each,independently of one another, from 1 to 6. n is preferably 1 and m ispreferably from 1 to 6.

Through a suitable choice of the meanings of R⁰ and X⁰, the addressingtimes, the threshold voltage, the gradient of the transmissioncharacteristic lines, etc., can be modified as desired. For example,1E-alkenyl radicals, 3E-alkenyl radicals, 2E-alkenyloxy radicals and thelike generally give shorter addressing times, improved nematictendencies and a higher ratio between the elastic constants k₃₃ (bend)and k₁₁ (splay) compared with alkyl and alkoxy radicals. 4-Alkenylradicals, 3-alkenyl radicals and the like generally give lower thresholdvoltages and lower values of k₃₃ /k₁₁ compared with alkyl and alkoxyradicals.

A --CH₂ CH₂ -- group in Z¹ generally results in higher values of k₃₃/k₁₁ compared with a simple covalent bond. Higher values of k₃₃ /k₁₁facilitate, for example, flatter transmission characteristic lines in TNcells with a 90° twist (for achieving grey tones) and steepertransmission characteristic lines in STN, SBE and OMI cells (greatermultiplexing ability), and vice versa.

The optimum mixing ratio of the compounds of the formulae I andII+III+IV+V depends substantially on the desired properties, on thechoice of the components of the formulae I, II, III, IV and/or V and onthe choice of any other components which may be present. Suitable mixingratios within the abovementioned range can easily be determined fromcase to case.

The total amount of compounds of the formulae I to XVI in the mixturesaccording to the invention is not crucial. The mixtures may thereforecontain one or more further components in order to optimize variousproperties. However, the effect observed on the addressing times and thethreshold voltage is generally greater the higher the totalconcentration of compounds of the formulae I to XI.

In a particularly preferred embodiment, the media according to theinvention contain compounds of the formulae II to V (preferably IIand/or III) in which X⁰ is OCF₃, OCHF₂, F, OCH═CF₂, OCF═CF₂ or OCF₂--CF₂ H. A favorable synergistic effect with the compounds of theformula I results in particularly advantageous properties.

For STN applications, the media preferably contain compounds selectedfrom the group comprising the formulae II to V in which X⁰ is preferablyOCHF₂ or CN.

The media according to the invention may furthermore contain a componentA comprising one or more compounds of the general formula I' having adielectric anisotropy of from -1.5 to +1.5 ##STR18## in which R¹ and R²are each, independently of one another, n-alkyl, n-alkoxy, ω-fluoroalkylor n-alkenyl having up to 9 carbon atoms, ##STR19## are each,independently of one another, 1,4-phenylene, 2- or3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene or 1,4-cyclohexenylene,

Z^(1') and Z^(2') are each, independently of one another, --CH₂ CH₂ --,--C.tbd.C--, --CO--O--, --O--CO-- or a single bond, and

n is 0, 1 or 2.

Component A preferably contains one or more compounds selected from thegroup comprising II1 to II7: ##STR20## in which R¹ and R² are as definedunder the formula I'.

Component A preferably additionally contains one or more compoundsselected from the group comprising II8 to II20: ##STR21## in which R¹and R² are as defined under the formula I', and the 1,4-phenylene groupsin II8 to II17 may each, independently of one another, also bemonosubstituted or polysubstituted by fluorine.

Furthermore, component A preferably additionally contains one or morecompounds selected from the group comprising II21 to II25: ##STR22## inwhich R¹ and R² are as defined under the formula I', and the1,4-phenylene groups in II21 to II25 may also each, independently of oneanother, be monosubstituted or polysubstituted by fluorine.

Finally, preferred mixtures of this type are those in which component Acontains one or more compounds selected from the group comprising II26and II27: ##STR23## in which C_(r) H_(2r+1) is a straight-chain alkylgroup having up to 7 carbon atoms and s is 0, 1, 2 or 3.

In some cases, the addition of compounds of the formula ##STR24## inwhich R¹ and R² are as defined under the formula I', and Z⁰ is a singlebond, --C₂ H₄ -- ##STR25## has proven advantageous for suppressingsmectic phases, although this may reduce the specific resistance. Inorder to achieve parameter combinations which are ideal for theapplication, a person skilled in the art can easily determine whetherand, if yes, in what amount these compounds may be added. Normally, lessthan 15%, in particular 5-10%, are used.

Preference is also given to liquid-crystal mixtures which contain one ormore compounds selected from the group comprising III' and IV':##STR26## in which R¹ and R² are as defined under formula I'.

The type and amount of the polar compounds having positive dielectricanisotropy is not crucial per se. A person skilled in the art can usesimple routine experiments to select suitable materials from the widerange of known and, in many cases, also commercially availablecomponents and base mixtures. The media according to the inventionpreferably contain one or more compounds of the formula I"' ##STR27## inwhich Z^(1'), Z^(2') and n are as defined under the formula I",##STR28## are each, independently of one another, 1,4-phenylene,trans-1,4-cyclohexylene or 3-fluoro-1,4-phenylene, and one of theradicals ##STR29## is alternatively trans-1,3-dioxane-2,5-diyl,pyrimidine-2,5-diyl, pyridine-2,5-diyl or 1,4-cyclohexenylene, R⁰ isn-alkyl, n-alkenyl, n-alkoxy or n-oxaalkyl, in each case having up to 9carbon atoms, Y¹ or Y² is H or F and X' is CN, halogen, CF₃, OCF₃ orOCHF₂.

In a preferred embodiment, the media according to the invention for STNor TN applications are based on compounds of the formula I" in which X'is CN. It goes without saying that smaller or larger proportions ofother compounds of the formula I" (X' not being CN) are also possible.For MLC applications, the media according to the invention preferablycontain only up to about 10% of nitriles of the formula I" (butpreferably no nitriles of the formula I", but instead compounds of theformula I' where X' is halogen, CF₃, OCF₃ or OCHF₂). These media arepreferably based on the compounds of the formulae II to XVI.

The media according to the invention preferably contain one or morecompounds having a dielectric anisotropy in the range -6≦Δε≦-1.5, of theformula I'" ##STR30## in which R¹, ##STR31## Z^(2'), n and R² are asdefined under formula I', for applications in which a small change inthe capacity of the pixel on switching is desired (for example MIMdisplays or TFT displays).

Preference is given to compounds of the formulae I^(1'") to I^(3'") :##STR32##

The construction of the STN and MLC displays according to the inventionfrom polarizers, electrode base plates and electrodes with surfacetreatment corresponds to the construction which is conventional fordisplays of this type. The term conventional construction here is widelydrawn and also covers all derivatives and modifications of the MLCdisplay, in particular also matrix display elements based on poly-SiTFTs or MIMs.

An essential difference between the displays according to the inventionand those customary hitherto based on the twisted nematic cell is,however, the choice of liquid-crystal parameters in the liquid-crystallayer.

The liquid-crystal mixtures which can be used according to the inventionare prepared in a manner which is conventional per se. In general, thedesired amount of the components used in the lesser amount is dissolvedin the components making up the principal constituents, expediently atelevated temperature. It is also possible to mix solutions of thecomponents in an organic solvent, for example in acetone, chloroform ormethanol, and, after thorough mixing, to remove the solvent again, forexample by distillation.

The dielectrics may also contain other additives known to those skilledin the art and described in the literature. For example, 0-15% ofpleochroic dyes or chiral dopes can be added.

C denotes a crystalline phase, S a smectic phase, S_(B) a smectic Bphase, N a nematic phase and I the isotropic phase.

V₁₀ denotes the voltage for 10% transmission (view angle perpendicularto the plate surface). t_(on) denotes the switch-on time and t_(off) theswitch-off time at an operating voltage corresponding to 2.5 times thevalue of V₁₀. An denotes the optical anisotropy and no the refractiveindex. Δε denotes the dielectric anisotropy (Δε=ε₁₁ -ε.sub.⊥, where ε₁₁is the dielectric constant parallel to the longitudinal molecular axesand ε.sub.⊥ is the dielectric constant perpendicular thereto). Theelectrooptical data were measured in a TN cell at the 1st minimum (i.e.at a d•Δn value of 0.5) at 20° C., unless expressly stated otherwise.The optical data were measured at 20° C., unless expressly statedotherwise.

In the present application and in the examples below, the structures ofthe liquid-crystal compounds are indicated by acronyms, with thetransformation into chemical formulae taking place in accordance withTables A and B below. All radicals C_(n) H_(2n+1) and C_(m) H_(2m+1) arestraight-chain alkyl radicals containing n or m carbon atoms. The codingin Table B is self-evident. In Table A, only the acronym for the basestructure is given. In individual cases, the acronym for the basestructure is followed, separated by a hyphen, by a code for thesubstituents R¹, R², L¹ and L² :

    ______________________________________                                        Code for R.sup.1                                                              R.sup.2, L.sup.1, L.sup.2                                                             R.sup.1          R.sup.2     L.sup.1                                                                           L.sup.2                              ______________________________________                                        nm      C.sub.n H.sub.2n+1                                                                             C.sub.m H.sub.2m+1                                                                        H   H                                    nOm     C.sub.n H.sub.2n+1                                                                             OC.sub.m H.sub.2m+1                                                                       H   H                                    nO.m    OC.sub.n H.sub.2n+1                                                                            C.sub.m H.sub.2m+1                                                                        H   H                                    n       C.sub.n H.sub.2n+1                                                                             CN          H   H                                    nN.F    C.sub.n H.sub.2n+1                                                                             CN          H   F                                    nF      C.sub.n H.sub.2n+1                                                                             F           H   H                                    nOF     OC.sub.n H.sub.2n+1                                                                            F           H   H                                    nCl     C.sub.n H.sub.2n+1                                                                             Cl          H   H                                    nF.F    C.sub.n H.sub.2n+1                                                                             F           H   F                                    nF.F.F  C.sub.n H.sub.2n+1                                                                             F           F   F                                    nCF.sub.3                                                                             C.sub.n H.sub.2n+1                                                                             CF.sub.3    H   H                                    nOCF.sub.3                                                                            C.sub.n H.sub.2n+1                                                                             OCF.sub.3   H   H                                    nOCF.sub.2                                                                            C.sub.n H.sub.2n+1                                                                             OCHF.sub.2  H   H                                    nS      C.sub.n H.sub.2n+1                                                                             NCS         H   H                                    rVsN    C.sub.r H.sub.2r+1 --CH═CH--C.sub.s H.sub.2s --                                            CN          H   H                                    rEsN    C.sub.r H.sub.2r+1 --O--C.sub.s H.sub.2s --                                                    CN          H   H                                    nAm     C.sub.n H.sub.2n+1                                                                             COOC.sub.m H.sub.2m+1                                                                     H   H                                    nOCCF.sub.2.F.F                                                                       C.sub.n H.sub.2n+1                                                                             OCH.sub.2 CF.sub.2 H                                                                      F   F                                    nOCF.sub.2.F.F                                                                        C.sub.n H.sub.2n+1                                                                             OCHF.sub.2  F   F                                    nCl.F.F C.sub.n H.sub.2n+1                                                                             Cl          F   F                                    nOCF.sub.3.F.F                                                                        C.sub.n H.sub.2n+1                                                                             OCF.sub.3   F   F                                    ______________________________________                                    

                  TABLE A                                                         ______________________________________                                         ##STR33##                                                                     ##STR34##                                                                     ##STR35##                                                                     ##STR36##                                                                     ##STR37##                                                                     ##STR38##                                                                     ##STR39##                                                                     ##STR40##                                                                     ##STR41##                                                                     ##STR42##                                                                     ##STR43##                                                                     ##STR44##                                                                     ##STR45##                                                                     ##STR46##                                                                     ##STR47##                                                                     ##STR48##                                                                     ##STR49##                                                                     ##STR50##                                                                     ##STR51##                                                                     ##STR52##                                                                     ##STR53##                                                                     ##STR54##                                                                     ##STR55##                                                                     ##STR56##                                                                    ______________________________________                                    

                  TABLE B                                                         ______________________________________                                         ##STR57##                                                                     ##STR58##                                                                     ##STR59##                                                                     ##STR60##                                                                     ##STR61##                                                                     ##STR62##                                                                     ##STR63##                                                                     ##STR64##                                                                     ##STR65##                                                                     ##STR66##                                                                     ##STR67##                                                                     ##STR68##                                                                     ##STR69##                                                                     ##STR70##                                                                     ##STR71##                                                                     ##STR72##                                                                     ##STR73##                                                                     ##STR74##                                                                     ##STR75##                                                                     ##STR76##                                                                     ##STR77##                                                                     ##STR78##                                                                     ##STR79##                                                                     ##STR80##                                                                     ##STR81##                                                                     ##STR82##                                                                     ##STR83##                                                                     ##STR84##                                                                     ##STR85##                                                                     ##STR86##                                                                    ______________________________________                                    

The examples below are intended to illustrate the invention withoutrepresenting a limitation. Above and below, percentages are by weight.All temperatures are given in degrees Celsius. m.p. denotes meltingpoint, c.p.=clearing point. Furthermore, C=crystalline state, N=nematicphase, S=smectic phase and I=isotropic phase. The numbers between thesesymbols represent the transition temperatures. Δn denotes opticalanisotropy (589 nm, 20° C.) and the viscosity (mm² /sec) was determinedat 20° C.

"Conventional work-up" means that, if necessary, water is added, themixture is extracted with dichloromethane, diethyl ether or toluene, theorganic phase is separated off, dried and evaporated, and the product ispurified by distillation under reduced pressure or crystallizationand/or chromatography. The following abbreviations are used:

DMEU 1,3-dimethyl-2-imidazolidinone

POT potassium tertiary-butoxide

THF tetrahydrofuran

pTSOH p-toluenesulphonic acid

EXAMPLE 1 ##STR87##

0.05 mol of 4-bromo-2,6-difluorotrifluoromethoxybenzene, 0.05 mol of4-(trans-4-n-propylcyclohexyl)-2,6-difluorophenylboronic acid and 1 g oftetrakistriphenylphosphinepalladium(O) catalyst are dissolved in 100 mlof toluene and 40 ml of ethanol, and 50 ml of 2M Na₂ CO₃ solution areadded. The mixture is refluxed for 4 hours and worked up by extraction.Purification by chromatography and crystallization gives the targetproduct: C 68 I; Δε=19.26; Δn=0.105.

The following compounds of the formula ##STR88## are preparedanalogously

    ______________________________________                                        R        L             X.sup.1                                                ______________________________________                                        H.sub.3 C                                                                              H             Cl                                                     H.sub.3 C                                                                              F             Cl                                                     H.sub.5 C.sub.2                                                                        H             Cl                                                     H.sub.5 C.sub.2                                                                        F             Cl                                                     H.sub.7 C.sub.3                                                                        H             Cl                                                     H.sub.7 C.sub.3                                                                        F             Cl                                                     H.sub.9 C.sub.4                                                                        H             Cl                                                     H.sub.9 C.sub.4                                                                        F             Cl                                                     H.sub.11 C.sub.5                                                                       H             Cl                                                     H.sub.11 C.sub.5                                                                       F             Cl                                                     H.sub.13 C.sub.6                                                                       H             Cl                                                     H.sub.13 C.sub.6                                                                       F             Cl                                                     H.sub.15 C.sub.7                                                                       H             Cl                                                     H.sub.15 C.sub.7                                                                       F             Cl                                                     H.sub.3 C                                                                              H             H                                                      H.sub.3 C                                                                              F             H                                                      H.sub.5 C.sub.2                                                                        H             H                                                      H.sub.5 C.sub.2                                                                        F             H                                                      H.sub.7 C.sub.3                                                                        H             H                                                      H.sub.7 C.sub.3                                                                        F             H                                                      H.sub.9 C.sub.4                                                                        H             H                                                      H.sub.9 C.sub.4                                                                        F             H                                                      H.sub.11 C.sub.5                                                                       H             H                                                      H.sub.11 C.sub.5                                                                       F             H                                                      H.sub.13 C.sub.6                                                                       H             H                                                      H.sub.13 C.sub.6                                                                       F             H                                                      H.sub.15 C.sub.7                                                                       H             H                                                      H.sub.15 C.sub.7                                                                       F             H                                                      H.sub.3 C                                                                              H             F                                                      H.sub.3 C                                                                              F             F                                                                             C 69 I; Δn = +0.0857;                                                   Δε = 19.33                               H.sub.5 C.sub.2                                                                        H             F                                                      H.sub.5 C.sub.2                                                                        F             F                                                                             C 78 I; Δn = +0.0878;                                                   Δε = 18.86                               H.sub.7 C.sub.3                                                                        H             F                                                      H.sub.9 C.sub.4                                                                        H             F                                                      H.sub.9 C.sub.4                                                                        F             F                                                      H.sub.11 C.sub.5                                                                       H             F                                                      H.sub.11 C.sub.5                                                                       F             F                                                                             C 78 I; Δn = +0,1014;                                                   Δε = 18,74                               H.sub.13 C.sub.6                                                                       H             F                                                      H.sub.13 C.sub.6                                                                       F             F                                                      H.sub.15 C.sub.7                                                                       H             F                                                      H.sub.15 C.sub.7                                                                       F             F                                                      ______________________________________                                    

Example 2 ##STR89## Step 2.1 ##STR90##

Under a protective gas, 0.43 mol of sodium 4-bromo-2,6-difluorophenoxideare dissolved in 1000 ml of THF and cooled to -60° C. 0.44 mol oftrifluoroacetyl chloride are introduced into the solution over thecourse of 0.5 h. The mixture is subsequently stirred at -60° C. for 1 h.The solution is allowed to warm to 10° C. and is evaporated. The residueis taken up in 1000 ml of hexane and stirred for 0.5 h. Finally, thesolvent is removed on a rotary evaporator. After addition of 500 ml ofdichloromethane, the product is subjected to conventional work-up.

Step 2.2 ##STR91##

SF₄ /HF is added to 0.05 mol of trifluoroacetate (step 2.1) analogouslyto I. L. Knunyants, G. G. Yakolson, Syntheses of FluoroorganicCompounds, p. 267. The mixture is heated in an autoclave at 150° C. for3 h and at 175° C. for 6 h. The mixture is then allowed to cool, and thegaseous products are passed into an alkali solution. After steamdistillation, ether is added to the residue, and the product is thensubjected to conventional work-up.

Step 2.3 ##STR92##

0.02 mol of pentafluoroethoxy-2,6-difluorobromobenzene are dissolved in75 ml of THF in an N₂ atmosphere, and the mixture is warmed to 60° C.with stirring. A solution comprising 0.037 mol of potassiumdihydrogenphosphate and 0.074 mol of sodium hydrogenphosphate in 40 mlof water and 0.46 g of tetrakis(triphenylphosphine) palladium(O)catalyst and 4-(trans-4-n-propylcyclohexyl)-2,6-difluorophenylboronicacid are added, and the mixture is refluxed for 24 h. The reactionmixture is allowed to cool to room temperature. After addition of methyltert-butyl ether, the mixture is subjected to customary work-up. C 78 N(72.2) I; Δn=0.116; Δε=18.88.

The following compounds are prepared analogously: ##STR93## MixtureExamples

    ______________________________________                                        Example 1                                                                     PCH--6F      3.5%    Cleariing point  °C.!:                                                                84                                        PCH--7F      3.0%    Viscocity at   46                                        CCP--2OCF.sub.2.F.F                                                                        16.0%   20° C.  mm.sup.2 s.sup.-1 !:                      CCP--3OCF.sub.2.F.F                                                                        15.0%   Δn  20° C., 589 nm!:                                                            0.1017                                    CCP--5OCF.sub.2.F.F                                                                        16.0%   V.sub.(10,0,20)  V!:                                                                         1.16                                      CUP--2F.F    6.0%    V.sub.(50,0,20)  V!:                                                                         1.45                                      CUP--3F.F    6.0%    V.sub.(90,0,20)  V!:                                                                         1.82                                      CUP--5F.F    5.0%                                                             CUP--2OCF.sub.2.F.F                                                                        6.0%                                                             CUP--3OCF.sub.2.F.F                                                                        6.0%                                                             CUP--5OCF.sub.2.F.F                                                                        6.0%                                                             CBC--33F     3.5%                                                             CBC--53F     4.0%                                                             CBC--55F     4.0%                                                             Example 2                                                                     PCH--5F      3.0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16.0%   Clearing point  °C.!:                                                                 +103                                      CCP--3OCF.sub.2.F.F                                                                        15.0%   Δn  589 nm, 20° C.!:                                                            +0.1086                                   CCP--5OCF.sub.2.F.F                                                                        16.0%   V.sub.(10,0,20)  V!:                                                                         1.26                                      CUP--2F.F    5.0%    V.sub.(90,0,20)  V!:                                                                         2.04                                      CUP--3F.F    5.0%                                                             CUP--5F.F    5.0%                                                             CUP--3OCF.sub.2.F.F                                                                        10.0%                                                            CUP--5OCF.sub.2.F.F                                                                        10.0%                                                            CBC--33F     5.0%                                                             CBC--53F     5.0%                                                             CBC--55F     5.0%                                                             Example 3                                                                     PCH--5F      3.0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16.0%   Clearing point  °C.!:                                                                 +100                                      CCP--3OCF.sub.2.F.F                                                                        15.0%   Δn  589 nm, 20° C.):                                                            +0.1077                                   CCP--5OCF.sub.2.F.F                                                                        16.0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    6.0%    V.sub.(10,0,20)  V!:                                                                         1.23                                      CUP--3F.F    6.0%    V.sub.(90,0,20)  V!:                                                                         1.95                                      CUP--5F.F.   5.0%                                                             CUP--2OCF.sub.2.F.F                                                                        6.0%                                                             CUP--3OCF.sub.2.F.F                                                                        6.0%                                                             CUP--5OCF.sub.2.F.F                                                                        6.0%                                                             CBC--33F     5.0%                                                             CBC--53F     5.0%                                                             CBC--55F     5.0%                                                             Example 4                                                                     PCH--6F      4,0%    Clearing point  °C.!                                                                  +78                                       PCH--7F      4,0%                                                             CCP--2OCF.sub.2.F.F                                                                        16,0%                                                            CCP--3OCF.sub.2.F.F                                                                        15,0%                                                            CCP--5OCF.sub.2.F.F                                                                        16,0%                                                            CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CBC--33F     3,0%                                                             CBC--53F     3,0%                                                             CBC--55F     4,0%                                                             Example 5                                                                     PCH--6F      3,5%    S → N  °C.!:                                                                   <-40                                      PCH--7F      3,0%    Clearing point  °C.!:                                                                 +84                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20°!C.!:                                                            0,1017                                    CCP--3OCF.sub.2.F.F                                                                        15.0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,24                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         2,01                                      CUP--3F.F    6,0%    ν 20:       50 cSt                                    CUP--5F.F    5,0%    ν -30:      4630 cSt                                  CUP--2OCF.sub.2.F.F                                                                        6,0%    HR (100°):                                                                            91%                                       CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CBC--33F     3,5%                                                             CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 6                                                                     PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +109                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,0998                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    6,0%    V.sub.(10,0,20)  V!:                                                                         1,27                                      CUP--3F.F    6,0%    V.sub.(90.0.20)  V!:                                                                         2,01                                      CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CBC--33F     5,0%                                                             CBC--34F     5,0%                                                             CBC--35F     5,0%                                                             Example 7                                                                     PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +97                                       CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1050                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,15                                      CUP--3F.F    5,0%    V.sub.(90.0.20)  V!:                                                                         1,82                                      CUP--5F.F    5.0%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            CUP--5OCF.sub.3.F.F                                                                        10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Example 8                                                                     PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +103                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1075                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz 20° C.!:                  CUP--2F.F    5,0%    V.sub.(10.0.20)  V!:                                                                         1,27                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         2,02                                      CUP--5F.F    5,0%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            CUP--5OCF.sub.3.F.F                                                                        10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Example 9                                                                     PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16.0%   Clearing point  °C.!:                                                                 +100                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20°!C.!:                                                            +0,1068                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    6,0%    V.sub.(10,0,20)  V!:                                                                         1,27                                      CUP--3F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,99                                      CUP--5F.F    5,0%                                                             CUP--2OCF.sub.3.F.F                                                                        6,0%                                                             CUP--3OCF.sub.3.F.F                                                                        6,0%                                                             CUP--5OCF.sub.3.F.F                                                                        6,0%                                                             CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Example 10                                                                    PCH--6F      4,0%    S → N  °C.!:                               PCH--7F      4,0%    Clearing point  °C.!:                                                                 +77                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            0,0980                                    CCP--3OCF.sub.2.F.F                                                                        15,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                     CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                     CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.3.F.F                                                                        6,0%                                                             CUP--3OCF.sub.3.F.F                                                                        6,0%                                                             CUP--5OCF.sub.3.F.F                                                                        6,0%                                                             CBC--33F     4,0%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 11                                                                    PCH--6F      6,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +85                                       CCP--3OCF.sub.2.F.F                                                                        15.0%   Δn  589 nm, 20° C.!:                                                            +0,1015                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    6,0%    V.sub.(10,0,20)  V!:                                                                         1,16                                      CUP--3F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,83                                      CUP--5F.F    5,0%                                                             CUP--2OCF.sub.3.F.F                                                                        6,0%                                                             CUP--3OCF.sub.3.F.F                                                                        6,0%                                                             CUP--5OCF.sub.3.F.F                                                                        6,0%                                                             CBC--33F     4,0%                                                             CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 12                                                                    PCH--6F      3,5%    S → N  °C.!:                               PCH--7F      3,0%    Clearing point  °C.!:                             CCP--2OCF.sub.2.F.F                                                                        12,0%   Δn (589 nm, 20° C.!:                        CCP--3OCF.sub.2.F.F                                                                        12,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        12,0%   V.sub.(10,0,20)  V!:                                     CUP--2F.F    5,0%    V.sub.(90,0,20)  V!                                      CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.3.F.F                                                                        5,0%                                                             CUP--3OCF.sub.3.F.F                                                                        5,0%                                                             CUP--5OCF.sub.3.F.F                                                                        5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       8,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       8,0%                                                             CBC--33F     3,5%                                                             CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 13                                                                    PCH--5F      5,0%    S → N  °C.!:                               PCH--7F      6,0%    Clearing point  °C.!:                                                                 +83                                       CCP--2OCF.sub.3                                                                            11,0%   Δn  589 nm, 20° C.!:                                                            +0,0882                                   CCP--3OCF.sub.3                                                                            12,0%   Δε  1 kHz, 20° C.!:                 CCP--4OCF.sub.3                                                                            10,0%   V.sub.(10,0,20)  V!:                                                                         1,40                                      CCP--5OCF.sub.3                                                                            12,0%   V.sub.(90,0,20)  V!:                                                                         2,18                                      CUP--3OCF.sub.3.F.F                                                                        12,0%                                                            BCH--5F.F.F  11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--5F.F.F  9,0%                                                             Example 14                                                                    PCH--5F      9,0%                                                             PCH--6F      7,2%                                                             PCH--7F      5,4%                                                             CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            6,3%                                                             CCP--5OCF.sub.3                                                                            9,9%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            Example 15                                                                    PCH--5F      5,0%    S → N (°C.!:                                                                   <-20                                      PCH--7F      6,0%    Clearing point  °C.!:                                                                 +80                                       CCP--2OCF.sub.3                                                                            11,0%   Δn  589 nm, 20° C.!:                                                            +0,0858                                   CCP--3OCF.sub.3                                                                            12,0%   V.sub.(10,0,20)  V!:                                                                         1,36                                      CCP--4OCF.sub.3                                                                            10,0%   V.sub.(90,0,20)  V!:                                                                         2.15                                      CCP--5OCF.sub.3                                                                            12,0%                                                            CUP--3OCF.sub.3.F.F                                                                        12,0%                                                            CUP--5OCF.sub.3.F.F                                                                        11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--3F.F.F  9,0%                                                             Example 16                                                                    PCH--5F      3,0%    S → N  °C.!:                                                                   <-30                                      CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +101                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1071                                   CCP--5OCF.sub.2.F.F                                                                        16.0%   V.sub.(10,0,20)  V!:                                                                         1,23                                      CUP--2F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,94                                      CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            CUP--5OCF.sub.3.F.F                                                                        10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Example 17                                                                    PCH--5F      8,5%                                                             PCH--6F      6,8%                                                             PCH--7F      5,1%                                                             CCP--2OCF.sub.3                                                                            6,8%                                                             CCP--3OCF.sub.3                                                                            10,2%                                                            CCP--4OCF.sub.3                                                                            6,0%                                                             CCP--5OCF.sub.3                                                                            9,3%                                                             BCH--3F.F    10,2%                                                            BCH--5F.F    8,5%                                                             ECCP--3OCF.sub.3                                                                           4,2%                                                             ECCP--5OCF.sub.3                                                                           4,2%                                                             CBC--33F     1,7%                                                             CBC--53F     1,7%                                                             CBC--55F     1,7%                                                             CUP--3OCF.sub.3.F.F                                                                        15,0%                                                            Example 18                                                                    PCH--5F      8,0%    Clearing point  °C.!:                                                                 75,6                                      PCH--6F      6,4%                                                             PCH--7F      4,8%                                                             CCP--2OCF.sub.3                                                                            6,4%                                                             CCP--3OCF.sub.3                                                                            9,6%                                                             CCP--4OCF.sub.3                                                                            5,6%                                                             CCP--5OCF.sub.3                                                                            8,8%                                                             BCH--3F.F    9,6%                                                             BCH--5F.F    8,0%                                                             ECCP--3OCF.sub.3                                                                           4,0%                                                             ECCP--5OCF.sub.3                                                                           4,0%                                                             CBC--33F     1,6%                                                             CBC--53F     1,6%                                                             CBC--55F     1,6%                                                             CUP--3OCF.sub.3.F.F                                                                        20,0%                                                            Example 19                                                                    PCH--6F      1,0%    Clearing point  °C.!:                                                                 +74                                       CCP--2OCF.sub.2.F.F                                                                        17,0%   Δn  589 nm, 20° C.!:                                                            +0,0994                                   CCP--3OCF.sub.2.F.F                                                                        17,0%   V.sub.(10,0,20)  V!:                                                                         1,00                                      CCP--5OCF.sub.2.F.F                                                                        17,0%   V.sub.(90,0,20)  V!:                                                                         1,59                                      CUP--2F.F    7,0%                                                             CUP--3F.F    7,0%                                                             CUP--5F.F    8,0%                                                             CUP--3OCF.sub.3.F.F                                                                        11,0%                                                            CUP--5OCF.sub.3.F.F                                                                        11,0%                                                            CBC--53F     2,0%                                                             CBC--55F     2,0%                                                             Example 20                                                                    PCH--6F      1,0%    Clearing point  °C.) :                                                                +83                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1025                                   CCP--3OCF.sub.2.F.F                                                                        17,0%   V.sub.(10,0,20)  V!:                                                                         1,11                                      CCP--5OCF.sub.2.F.F                                                                        17,0%   V.sub.(90,0,20)  V!:                                                                         1,80                                      CUP--2F.F    6,0%                                                             CUP--3F.F    7,0%                                                             CUP--5F.F    8,0%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            CUP--5OCF.sub.3.F.F                                                                        11,0%                                                            CBC--53F     3,0%                                                             CBC--55F     4,0%                                                             Example 21                                                                    CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 86                                        CCP--3OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1046                                   CCP--5OCF.sub.2.F.F                                                                        17,0%   V.sub.(10,0,20)  V!:                                                                         1,10                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,76                                      CUP--3F.F    7,0%                                                             CUP--5F.F    8,0%                                                             CUP--3OCF.sub.3.F.F                                                                        11,0%                                                            CUP--5OCF.sub.3.F.F                                                                        11,0%                                                            CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 22                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 80,6                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0954                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,67                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--1OCF.sub.3.F.F                                                                        10,0%                                                            Example 23                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 81,8                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0956                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,59                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--2OCF.sub.3.F.F                                                                        10,0%                                                            Example 24                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 84,5                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0974                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,68                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            Example 25                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 85,2                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0970                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,60                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--5OCF.sub.3.F.F                                                                        10,0%                                                            Example 26                                                                    PCH--5F      5,0%    Clearing point  °C.!:                                                                 +81                                       PCH--7F      6,0%    Δn  589 nm, 20° C.!:                                                            0,0884                                    CCP--2OCF.sub.3                                                                            11,0%   V.sub.(10,0,20)  V!:                                                                         1,42                                      CCP--3OCF.sub.3                                                                            12,0%   V.sub.(90,0,20)  V!:                                                                         2,22                                      CCP--4OCF.sub.3                                                                            10,0%                                                            CCP--5OCF.sub.3                                                                            12,0%                                                            CUP--2OCF.sub.2.F.F                                                                        12,0%                                                            BCH--5F.F.F  11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--5F.F.F  9,0%                                                             Example 27                                                                    PCH--5F      5,0%    Clearing point  °C.!:                                                                 +84                                       PCH--7F      6,0%    Δn  589 nm, 20° C.!:                                                            0,0903                                    CCP--2OCF.sub.3                                                                            11,0%   V.sub.(10,0,20)  V!:                                                                         1,45                                      CCP--3OCF.sub.3                                                                            12,0%   V.sub.(90,0,20)  V!:                                                                         2,30                                      CCP--4OCF.sub.3                                                                            10,0%                                                            CCP--5OCF.sub.3                                                                            12,0%                                                            CUP--3CCF2.F.F                                                                             12,0%                                                            BCH--5F.F.F  11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--5F.F.F  9,0%                                                             Example 28                                                                    PCH--5F      5,0%    Clearing point  °C.!:                                                                 +83                                       PCH--7F      6,0%    Δn  589 nm, 20° C.!:                                                            0,0908                                    CCP--2OCF.sub.3                                                                            11,0%   V.sub.(10,0,20)  V!:                                                                         1,46                                      CCP--3OCF.sub.3                                                                            12,0%   V.sub.(90,0,20)  V!:                                                                         2,27                                      CCP--4OCF.sub.3                                                                            10,0%                                                            CCP--5OCF.sub.3                                                                            12,0%                                                            BCH--3F.F.F  12,0%                                                            CUP--5OCF.sub.2.F.F                                                                        11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--5F.F.F  9,0%                                                             Example 29                                                                    PCH--5F      5,0%    Clearing point  °C.!:                                                                 +81                                       PCH--7F      6,0%    Δn  589 nm, 20° C.!:                                                            0,0884                                    CCP--2OCF.sub.3                                                                            11,0%   V.sub.(10,0,20)  V!:                                                                         1,23                                      CCP--3OCF.sub.3                                                                            12,0%   V.sub.(90,0,20)  V!:                                                                         1,95                                      CCP--4OCF.sub.3                                                                            10,0%                                                            CCP--5OCF.sub.3                                                                            12,0%                                                            CUP--2OCF.sub.2.F.F                                                                        12,0%                                                            BCH--5F.F.F  11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--5F.F.F  9,0%                                                             Example 30                                                                    PCH--6F      5,0%    Clearing point  °C.!:                                                                 +85                                       CCP--2OCF.sub.2.F.F                                                                        19,0%   Δn  589 nm, 20° C.!:                                                            0,0993                                    CCP--3OCF.sub.2.F.F                                                                        19,0%   V.sub.(10,0,20)  V!:                                                                         1,23                                      CCP--5OCF.sub.2.F.F                                                                        19,0%   V.sub.(90,0,20)  V!:                                                                         1,89                                      CUP--2F.F    5,0%                                                             CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        5,0%                                                             CUP--3OCF.sub.2.F.F                                                                        5,0%                                                             CUP--5OCF.sub.2.F.F                                                                        5,0%                                                             CBC--33F     4,0%                                                             CBC--53F     4,0%                                                             Example 31                                                                    PCH--6F      3,5%    Clearing point  °C.!:                                                                 +92                                       PCH--7F      3,0%    Δn  589 nm, 20° C.!:                                                            +0,0942                                   CCP--2OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,25                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(90,0,20)  V!:                                                                         1,94                                      CCP--5OCF.sub.2.F.F                                                                        16,0%                                                            CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CCPC--33     3,5%                                                             CCPC--34     4,0%                                                             CCPC--35     4,0%                                                             Example 32                                                                    PCH--6F      4,5%    Clearing point  °C.!:                                                                 +86                                       PCH--7F      3,0%    Δn  589 nm, 20° C.!:                                                            +0,0952                                   CCP--2OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,21                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(90,0,20)  V!:                                                                         1,88                                      CCP--5OCF.sub.2.F.F                                                                        16,0%                                                            CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CCPC--33     2,5%                                                             CCPC--34     4,0%                                                             CCPC--35     4,0%                                                             Example 33                                                                    PCH--5F      4,5%    Clearing point  °C.!:                                                                 +101                                      CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 mn, 20° C.!:                                                            +0,0984                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,22                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,92                                      CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CCPC--33     4,0%                                                             CCPC--34     4,5%                                                             CCPC--35     5,0%                                                             Example 34                                                                    CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 96                                        CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1010                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,27                                      CUP--2F.F    6,0%    V.sub.(90.0.20)  V!:                                                                         1,94                                      CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CBC--33F     6,0%                                                             CBC--53F     6,0%                                                             CBC--55F     6,0%                                                             Example 35                                                                    PCH--6F      3,5%    Clearing point  °C.!:                                                                 96                                        PCH--7F      8,0%    Δn  589 nm, 20° C.!:                                                            +0,1010                                   CCP--2OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,38                                      CCP--3OCF.sub.2.F.F                                                                        15,9%   V.sub.(90,0,20)  V!:                                                                         2,10                                      CCP--5OCF.sub.2.F.F                                                                        16,0%                                                            CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        6,0%                                                             CUP--3OCF.sub.2.F.F                                                                        6,0%                                                             CUP--5OCF.sub.2.F.F                                                                        6,0%                                                             CBC--33F     3,5%                                                             CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 36                                                                    PCH--5F      8,5%    Clearing point  °C.!:                                                                 80                                        PCH--6F      6,8%                                                             PCH--7F      5,1%                                                             CCP--2OCF.sub.3                                                                            6,8%                                                             CCP--3OCF.sub.3                                                                            10,2%                                                            CCP--4OCF.sub.3                                                                            6,0%                                                             CCP--5OCF.sub.3                                                                            9,3%                                                             BCH--3F.F    10,2%                                                            BCH--5F.F    8,5%                                                             ECCP--3OCF.sub.3                                                                           4,2%                                                             ECCP--5OCF.sub.3                                                                           4,2%                                                             CBC--33F     1,7%                                                             CBC--53F     1,7%                                                             CBC--55F     1,7%                                                             CUP--3OCF.sub.2.F.F                                                                        15,0%                                                            Example 37                                                                    PCH--7F      1,0%    Clearing point  °C.!:                                                                 +84                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1050                                   CCP--3OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,09                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,74                                      CUP--2F.F    5,0%                                                             CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--2OCF.sub.2.F.F                                                                        5,0%                                                             CUP--3OCF.sub.2.F.F                                                                        5,0%                                                             CUP--5OCF.sub.2.F.F                                                                        5,0%                                                             CUP--2OCCF.sub.2.F.F                                                                       5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       5,0%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 38                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 +81,6                                     PCH--6F      7,2%    Δn  589 nm, 20° C.):                                                            0,0965                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,17                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--2OCF.sub.2.F.F                                                                        10,0%                                                            Example 39                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 84,0                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0980                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,18                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--3OCF.sub.3.F.F                                                                        10,0%                                                            Example 40                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 84,7                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0975                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,21                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--5OCF.sub.2.F.F                                                                        10,0%                                                            Example 41                                                                    PCH--6F      4,5%    S → N  °C.!:                                                                   <-40                                      PCH--7F      4,0%    Clearing point  °C.!:                                                                 +84                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1012                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,17                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(50,0,20)  V!:                                                                         1,47                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,87                                      CUP--3F.F    6,0%    ν 20:       44 cSt                                    CUP--5F.F    5,0%    ν -40:      19000 cSt                                 CUP--3OCCF.sub.2.F.F                                                                       9,0%    HR (100° C.):                                                                         92%                                       CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,5%                                                             CBC--55F     3,0%                                                             Example 42                                                                    PCH--5F      3,0%    S → N  °C.):                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +109                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.):                                                            +0,1111                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,29                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         2,03                                      CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       10,0%                                                            CUP--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Example 43                                                                    PCH--5F      6,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +96                                       CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1061                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,24                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,92                                      CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       10,0%                                                            CUP--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     4,0%                                                             CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 44                                                                    PCH--5F      5,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +100                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1077                                   CCP--5OCF.sub.2.F.F --                                                                     16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,25                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,97                                      CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       10,0%                                                            CUP--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     4,5%                                                             CBC--55F     3,5%                                                             Example 45                                                                    PCH--6F      3,5%    S → N  °C.!:                               PCH--7F      3,0%    Clearing point  °C.!:                                                                 +88                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1036                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,14                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,79                                      CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       10,0%                                                            CUP--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     3,5%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 46                                                                    PCH--6F      5,5%    S → N  °C.!:                               PCH--7F      5,0%    CIearing point  °C.!:                                                                 +81                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,0994                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,21                                      CUP--2F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,88                                      CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       9,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 47                                                                    PCH--6F      4,5%    S → N  °C.!:                                                                   <-40                                      PCH--7F      4,0%    Clearing point  °C.!:                                                                 +84                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0.1012                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,18                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,87                                      CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       9,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 48                                                                    PCH--6F      4,5%    S → N (°C.!:                                                                   <-40                                      PCH--7F      4,0%    Clearing point  °C.!:                                                                 +93                                       CCP--2OCF.sub.2.F.F                                                                        8,0%    Δn (589 nm, 20° C.!:                                                            +0,1036                                   CCP--3OCF.sub.2.F.F                                                                        8,0%    Δε (1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        8,0%    V.sub.(10,0,20)  V!:                                                                         1,21                                      CCP--2OCCF.sub.2.F.F                                                                       8,0%    V.sub.(90,0,20)  V!:                                                                         1,92                                      CCP--3OCCF.sub.2.F.F                                                                       7,0%                                                             CCP--5OCCF.sub.2.F.F                                                                       8,0%                                                             CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       9,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 49                                                                    PCH--6F      4,5%    S → N  °C.!:                                                                   <-40                                      PCH--7F      4,0%    Clearing point  °C.!:                                                                 +96                                       CCP--2OCCF.sub.2.F.F                                                                       16,0%   Δn  589 nm, 20° C.!:                                                            +0,108                                    CCP--3OCCF.sub.2.F.F                                                                       15,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCCF.sub.2.F.F                                                                       16,0%   V.sub.(10,0,20)  V!:                                                                         1,23                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,95                                      CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       9,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 50                                                                    PCH--EF      4,5%    S → N  °C.!:                                                                   <-40                                      PCH--7F      4,0%    Clearing point  °C.!:                                                                 +87                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,103                                    CCP--3OCF.sub.2.F.F                                                                        15,0%   Δε  1 kHz, 20° C.!:                 CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,15                                      CUP--2OCH═CF.sub.2.F.F                                                                 6,0%    V.sub.(90,0,20)  V!:                                                                         1,86                                      CUP--3OCH═CF.sub.2.F.F                                                                 6,0%                                                             CUP--5OCH═CF.sub.2.F.F                                                                 5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       9,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 51                                                                    PCH--6F      4,5%    S → N  °C.!:                                                                   <-40                                      PCH--7F      4,0%    Clearing point  °C.!:                                                                 93                                        CCP--2OCF═CF.sub.2.F.F                                                                 16,0%   Δn  589 nm, 20° C.!:                                                            +0,105                                    CCP--3OCF═CF.sub.2.F.F                                                                 15,0%   Δε (1 kHz, 20° C.!:                 CCP--5OCF═CF.sub.2.F.F                                                                 16,0%   V.sub.(10,0,20)  V!:                                                                         1,13                                      CUP--2F.F    6,0%    V.sub.(90,0,20)  V!:                                                                         1,80                                      CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       9,0%                                                             CUP--5OCCF.sub.2.F.F                                                                       9,0%                                                             CBC--33F     3,5%                                                             CBC--53F     3,5%                                                             CBC--55F     3,0%                                                             Example 52                                                                    PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +119                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.):                                                            +0,1158                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,51                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         2,34                                      CUP--5F.F    5,0%                                                             BCH--3OCCF.sub.2.F.F                                                                       10,0%                                                            BCH--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Exauiple 53                                                                   PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +96                                       CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1061                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20) (V!:                                                                         1,24                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,92                                      CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       10,0%                                                            CUP--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     4,0%                                                             CBC--53F     4,0%                                                             CBC--55F     4,0%                                                             Example 54                                                                    PCH--5F      5,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +100                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1077                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,25                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,97                                      CUP--5F.F    5,0%                                                             CUP--3OCCF.sub.2.F.F                                                                       10,0%                                                            CUP--5OCCF.sub.2.F.F                                                                       10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     4,5%                                                             CBC--55F     3,5%                                                             Example 55                                                                    PCH--5F      5,0%    S → N  °C.!:                               PCH--7F      6,0%    Clearing point  °C.!:                                                                 +85                                       CCP--2OCF.sub.3                                                                            11,0%   Δn  589 nm, 20° C.!:                                                            +0,0922                                   CCP--3OCF.sub.3                                                                            12,0%   Δε  1 kHz, 20° C.!:                 CCP--4OCF.sub.3                                                                            10,0%   V.sub.(10,0,20)  V!:                                                                         1,41                                      CCP--5OCF.sub.3                                                                            12,0%   V.sub.(90,0,20)  V!:                                                                         2,20                                      CUP--3OCH═CF.sub.2.F.F                                                                 12,0%                                                            CUP--5OCH═CF.sub.2.F.F                                                                 11,0%                                                            CCP--3F.F.F  12,0%                                                            CCP--5F.F.F  9,0%                                                             Example 56                                                                    PCH--5F      3,0%    S → N  °C.!:                               CCP--2OCF.sub.2.F.F                                                                        16,0%   Clearing point  °C.!:                                                                 +106                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   Δn  589 nm, 20° C.!:                                                            +0,1117                                   CCP--5OCF.sub.2.F.F                                                                        16,0%   Δε  1 kHz, 20° C.!:                 CUP--2F.F    5,0%    V.sub.(10,0,20)  V!:                                                                         1,24                                      CUP--3F.F    5,0%    V.sub.(90,0,20)  V!:                                                                         1,94                                      CUP--5F.F    5,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0%                                                            CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     5,0%                                                             Example 57                                                                    PCH--5F      4,5%    Clearing point  °C.!:                                                                 +99                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1091                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,12                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,81                                      CUP--2F.F    5,0%                                                             CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0%                                                            CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     4,5%                                                             CBC--55F     4,0%                                                             Example 58                                                                    PCH--5F      4,0%    Clearing point  °C.!:                                                                 +101                                      CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn (589 nm, 20° C.!:                                                            +0,1098                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,04                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,68                                      CUP--2F.F    5,0%                                                             CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0%                                                            CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     4,0%                                                             Example 59                                                                    PCH--6F      4,0%    Clearing point  °C.!:                                                                 +85                                       PCH--7F      3,0%    Δn  589 nm, 20° C.!:                                                            +0,1030                                   CCP--2OCF.sub.2.F.F                                                                        16,0%   V.sub.(10,0,20)  V!:                                                                         1,15                                      CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(90,0,20)  V!:                                                                         1,79                                      CCP--5OCF.sub.2.F.F                                                                        17,0%                                                            CUP--2F.F    6,0%                                                             CUP--3F.F    6,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 9,0%                                                             CUP--5OCH═CF.sub.2.F.F                                                                 9,0%                                                             CBC--33F     4,0%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 60                                                                    PCH--6F      3,0%    Clearing point  °C.!:                                                                 +87                                       CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1071                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,11                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,74                                      CUP--2F.F    7,0%                                                             CUP--3F.F    7,0%                                                             CUP--5F.F    7,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0                                                             CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            CBC--33F     3,0%                                                             CBC--53F     3,0%                                                             CBC--55F     3,0%                                                             Example 61                                                                    PCH--5F      3,0%    Clearing point  °C.!:                                                                 +84                                       CCP--2OCF.sub.2.F.F                                                                        17,0%   Δn  589 nm, 20° C.!:                                                            +0,1061                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,10                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,72                                      CUP--2F.F    7,0%                                                             CUP--3F.F    7,0%                                                             CUP--5F.F    7,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0%                                                            CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            CBC--33F     3,0%                                                             CBC--53F     3,0%                                                             CBC--55F     2,0%                                                             Example 62                                                                    PCH--5F      4,0%    Clearing point  °C.!:                                                                 +101                                      CCP--2OCF.sub.2.F.F                                                                        16,0%   Δn  589 nm, 20° C.!:                                                            +0,1105                                   CCP--3OCF.sub.2.F.F                                                                        15,0%   V.sub.(10,0,20)  V!:                                                                         1,24                                      CCP--5OCF.sub.2.F.F                                                                        16,0%   V.sub.(90,0,20)  V!:                                                                         1,93                                      CUP--2F.F    5,0%                                                             CUP--3F.F    5,0%                                                             CUP--5F.F    5,0%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0%                                                            CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            CBC--33F     5,0%                                                             CBC--53F     5,0%                                                             CBC--55F     4,0%                                                             Example 63                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 84,6                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0996                                    PCH--7F      5,4%.   Δε  1 kHz, 20° C.!:                                                     6,37                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--2OCH═CF.sub.2.F.F                                                                 10,0%                                                            Example 64                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 87,3                                      PCH--6F      7,2%    Δn  589 nm, 20°C.!:                                                             0,0995                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,22                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--5OCH═CF.sub.2.F.F                                                                 10,0%                                                            Example 65                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 86,6                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            0,0994                                    PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,48                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--3OCH═CF.sub.2.F.F                                                                 10,0%                                                            Example 66                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 87,6                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            +0,0985                                   PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,61                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--3OC.sub.2 F.sub.5.F.F                                                                 10,0%                                                            Example 67                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 89                                        PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            +0,0985                                   PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,55                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--5OC.sub.2 F.sub.5.F.F                                                                 10,0%                                                            Example 68                                                                    PCH--5F      9,0%    Clearing point  °C.!:                                                                 90,3                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            +0,0993                                   PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,22                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--5OC.sub.2 F.sub.5.F                                                                   10,0%                                                            Example 69                                                                    PCH--5F      9,0%    Clearing point  °C!:                                                                  89,3                                      PCH--6F      7,2%    Δn  589 nm, 20° C.!:                                                            +0,0993                                   PCH--7F      5,4%    Δε  1 kHz, 20° C.!:                                                     6,27                                      CCP--2OCF.sub.3                                                                            7,2%                                                             CCP--3OCF.sub.3                                                                            10,8%                                                            CCP--4OCF.sub.3                                                                            8,1%                                                             CCP--5OCF.sub.3                                                                            8,1%                                                             BCH--3F.F    10,8%                                                            BCH--5F.F    9,0%                                                             ECCP--3OCF.sub.3                                                                           4,5%                                                             ECCP--5OCF.sub.3                                                                           4,5%                                                             CBC--33F     1,8%                                                             CBC--53F     1,8%                                                             CBC--55F     1,8%                                                             CUP--3OC.sub.2 F.sub.5.F                                                                   10,0%                                                            ______________________________________                                    

We claim:
 1. A liquid-crystalline medium based on a mixture of polarcompounds having positive dielectric anisotropy, which comprises one ormore compounds of the formula I ##STR94## in which R is H, an alkyl oralkenyl radical having 1 to 15 carbon atoms which is unsubstituted or,optionally, has one or more CH₂ groups replaced, in each caseindependently of one another, by --O--, --S--, --⋄--, --CO--, --CO--O--,--O--CO-- or --O--CO--O--, such that O atoms are not linked directly toone another,A¹ and A² are each, independently of one another, a(a)trans-1,4-cyclohexylene racial, which is optionally substituted by oneor two fluorine atoms and in which one or more non-adjacent CH₂ groupsare optionally replaced independently by --O-- or --S--, (b)1,4-phenylene radical in which one or two CH groups are optionallyreplaced by N, or (c) radical selected from the group consisting of1,4-cyclohexenylene, 1,4-bicyclo(2,2,2)-octylene, piperidine-1,4-diyl,naphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, Z¹ andZ² are each, independently of one another, --CO--O--, --O--CO--, --CH₂O--, --OCH₂ --, --CH═CH--, --C.tbd.C-- and one of the radicals Z¹ and Z²is optionally --(CH₂)₄ -- or --CH═CH--CH₂ CH₂ --, X is halogenatedalkyl, alkoxy, alkenyl or alkenyloxy, in each case having 1 to 6 carbonatoms, L is F and also H when X is OC₂ F₅, and m is 0, 1 or
 2. 2. Themedium according to claim 1, further comprising one or more compoundsselected from the group consisting of the compounds of formulae II, III,IV and V: ##STR95## in which the individual radicals are as definedbelow: R⁰ : alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having1 to 7 carbon atoms,X⁰ : F, Cl, CF₃, OCF₃, OCHF₂, OCH═CF₂, OCF═CF₂,OCFH═CF₂ H or OCF₂ --CF₂ H, Y¹ and Y² : each, independently of oneanother, H or F r: 0 or
 1. 3. The medium according to claim 1, furthercomprising one or more compounds selected from the group consisting ofcompounds of formulae VI to XII: ##STR96## in which the radicals R⁰, X⁰,Y¹ and Y² are as defined below:R⁰ : alkyl, oxaalkyl, fluoroalkyl oralkenyl, in each case having 1 to 7 carbon atoms, X⁰ : F, Cl,CF₃,OCF₃,OCHF₂, OCH═CF₂, OCF═CF₂, OCFH--CF₂ H or OCF₂ --CF₂ H, Y¹ and Y²: each, independently of one another, H or F.
 4. The medium according toclaim 2, wherein the proportion of compounds of the formulae I to Vtogether is at least 50% by weight in the total mixture.
 5. The mediumaccording to claim 1, wherein the proportion of compounds of the formulaI is from 3 to 80% by weight in the total mixture.
 6. The mediumaccording to claim 2, wherein the proportion of compounds of theformulae II to V is from 20 to 80% by weight in the total mixture. 7.The medium according to claim 2, further comprising one or morecompounds selected from the group consisting of compounds of formulae VIto XII: ##STR97## in which the radicals R⁰, X⁰ , Y¹ and Y² are asdefined below:R⁰ : alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each casehaving 1 to 7 carbon atoms, X⁰ : F, Cl, CF₃,OCF₃,OCHF₂, OCH═CF₂,OCF+CF₂, OCFH--CF₂ H or OCF₂ --CF₂ H, Y¹ and Y² : each, independently ofone another, H or F.
 8. Electrooptical liquid-crystal display containinga liquid-crystalline medium according to claim
 1. 9. The mediumaccording to claim 7, which consists essentially of compounds of theformulae I to XII.
 10. The liquid-crystalline medium of claim 1, havinga nematic phase range of -20° C. to 80° C., a clearing point above 80°C., a dielectric anisotropy of ≧6 and a TN threshold of below 2.0 V. 11.The liquid-crystalline medium of claim 2, which comprises one or morecompounds of the formulae II or III wherein X⁰ is OCF₃, OCHF₂, F,OCH═CF₂, OCF═CF₂, or OCF₂ --CF₂ H.
 12. The liquid-crystalline medium ofclaim 1, which contains only up to about 10% by weight of compoundshaving nitrile groups.
 13. The liquid-crystalline medium of claim 1,which contains no compounds having nitrile groups.
 14. Theliquid-crystalline medium of claim 1, wherein in formula I, L is F. 15.A liquid crystal mixture based on a mixture of polar compounds havingpositive dielectric anisotropy which comprises one or more compounds ofthe formula ##STR98## in which R is H, an alkyl or alkenyl having 1 to15 carbon atoms which is unsubstituted or, optionally, has one or moreCH2 groups replaced, in each case independently of one another, by--O--, --S--, ⋄, --CO, --CO--O, --O--CO-- or --O--CO--O, such that Oatoms are not linked directly to one another.
 16. A liquid crystalmixture based on a mixture of polar compounds having no positivedielectric anisotropy which comprises one or more compounds of theformula ##STR99## in which R is H, an alkyl or alkenyl having 1 to 15carbon atoms which is unsubstituted or, optionally, has one or more CH2groups replaced, in each case independently of one another, by --O--,--S--, ⋄, --CO, --CO--O, --O--CO-- or --O--CO--O, such that O atoms arenot linked directly to one another.